Update minimal JAX version to latest (0.3.16).
0.3.16 includes https://github.com/google/jax/pull/11807, which supports more flexible sharding constraints under vmap (see also flax/linen/partitioning.py).
0.3.16 removes jax.tree_util.tree_multimap, so we are also updating to the latest jgraph version (in which tree_multimap has been replaced).
PiperOrigin-RevId: 467265619
